1. Field of the Invention
The present invention relates to a combined type pressure gauge, and the manufacturing method of the combined type pressure gauge.
2. Description of the Related Art
In the pressure gauge described in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2002-520613, a protective tube having a flange for being connected to a vacuum apparatus etc. and a supporting plate are welded via an elastic spring. To the supporting plate, a diaphragm made of ceramic is arranged via a glass seal tube, and the space surrounded by these forms a reference vacuum chamber. Here, when gas pressure is applied to the diaphragm from the outside, the diaphragm is deflected to the reference vacuum chamber side. On the diaphragm and the surface of the supporting plate of the reference vacuum chamber side, electroconductive electrodes are formed, respectively, and, by measuring the capacitance between both electrodes, the gas pressure can be measured.
Furthermore, to the pressure gauge of the related art, a protective ring is arranged so as to surround the diaphragm, and, to the outside thereof, two filaments, which are fixed by supporting poles, are arranged. The filament is a constituent of a Pirani pressure gauge, wherein the pressure can be measured from the amount of heat of the filament taken away by the gas (The filament is made of a material of platinum, tungsten or nickel, or an alloy containing at least one of these metals, and the resistivity of the filament changes significantly in accordance with the temperature. That is, the resistivity thereof depends on the amount of heat that is taken away from the filament by the gas, that is, the pressure of the gas). In addition, a system is created in which the electric information of the Pirani pressure gauge is output to the outside from a electrical terminal different from the electrical terminal of the capacitive pressure gauge, and in which the electric information is transformed to electric information corresponding to the gas pressure by an electric circuit and is finally displayed as a pressure value.
Japanese Patent Application Laid-open Publication No. 2008-209284 discloses the production of the Pirani pressure gauge and a diaphragm pressure gauge by using a MEMS (Micro-Electro-Mechanical Systems) technology as a pressure measurement apparatus.
The combined type pressure gauge in Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2002-520613 is, however, one formed by arranging a capacitive pressure gauge and a Pirani pressure gauge, formed through separate manufacturing processes, simply assemble together. Accordingly, the cost reduction effect upon the production is low. Moreover, since two pressure gauges are arranged in a small place, the lowering of manufacturing efficiency or, potentially, the lowering of yield is caused to thereby increase the manufacturing cost, occasionally.
Japanese Patent Application Laid-open Publication No. 2008-209284 does not disclose a specific manufacturing method of producing simultaneously a Pirani pressure gauge and a diaphragm pressure gauge on the same substrate. Therefore, the processes to from these gauges cannot be efficient and the manufacturing cost cannot also be reduced.